The present invention relates to a cyclone dust collector, and more particularly, to a device for reducing the intensity of turbulence generated in a cyclone dust collector.
Generally, a vacuum cleaner sucks indoor air using suction force and separates various kinds of foreign materials from the air to collect the foreign materials. There are various types of cyclone dust collectors, and specially there are a cyclone dust collector in which an inlet of air and an outlet of air are in forward direction, and another cyclone dust collector in which an inlet or air and an outlet of air are in reverse direction(or tangent direction).
U.S. Pat. Nos. 3,870,486, 4,853,008, 4,373,228, 4,643,738, 4,593,429, 5,080,697, 5,135,552, and 5,160,356 disclose cyclone dust collectors in which an air flow is in reverse direction. U.S. Pat. No. 5,350,432 discloses a cyclone dust collector in which an air flow is in forward direction.
A cyclone dust collector in which an air inlet flow is reverse to an air outlet flow will be described with reference to FIG. 1 to FIG. 3.
In other words, a related art cyclone dust collector includes a cone-shaped cyclone body 10, an air inlet passage 11 for sucking indoor air and foreign materials, an air outlet passage 12 for discharging air, and a collector tub 13 for collecting the foreign materials separated from the air.
The air inlet passage 11 extends to the cyclone body 10 along tangent direction. The air outlet passage 12 has one end which passes through a top end of the cyclone body 10 to be located inside the cyclone body 10. The collector tub 13 is located at the bottom of the cyclone body 10 and communicates with the inside of the cyclone body 10 by a foreign material outlet hole 10a. 
Thus, if a suction force is generated inside the cyclone body 10, air containing dust flows into the cyclone body 10 through the air inlet passage 11. At this time, the air inlet passage 11 extends from an outer circumference of the cyclone body 10 to tangent direction so that a centrifugal force is applied to the air flowed into the cyclone body 10. That is to say, the air and foreign materials instantaneously flowed into the cyclone body 10 rotate along an inner wall of the cyclone body 10 so that a centrifugal force is generated. Accordingly, the foreign materials having a mass are separated from the air having almost no mass, and flow along the inner wall of the cyclone body 10. Then, the foreign materials descend by its tare, so that the foreign materials are collected into the collector tub 13 through the foreign material outlet hole 10a. 
In other words, by the relation of the following equation 1, the air having a mass almost close to 0 is not subjected to a centrifugal force while the foreign materials having a mass rotate along the inner wall of the cyclone body 10 by a centrifugal force.
F=mexcfx892,xe2x80x83xe2x80x83[Equation 1]
where F is a centrifugal force, m is a mass, e is a distance between the center of the cyclone body and its inner wall, and xcfx89 is an angular velocity.
The air separated from the foreign materials is discharged out through the air outlet passage 12 along discharge air that ascends along the center of the cyclone body 10.
However, the descending air sucked into the cyclone body 10 interferes with a discharge air that ascends from the bottom of the cyclone body 10. Thus, a turbulence area is generated as shown in a portion xe2x80x9cAxe2x80x9d of FIG. 2.
The interference is caused because of a rotative force of the discharge air and a smaller sectional area of the cyclone body 10 than a sectional are of the air outlet passage 12.
The turbulence flow increases noise and causes pressure loss when the cyclone collector is operating, thereby reducing collecting efficiency of the dust. In other words, the dust flowing into the bottom of the cyclone body 10 and the collector body 13 is contained in the discharge air which is discharged through the air outlet passage 12, thereby reducing the overall collecting efficiency.
Particularly, since the foreign materials which are not discharged are rotating at the bottom of the cyclone body 10, where the dust discharge hole 10a is located, the foreign materials are likely to be contained in the discharge air.
Also, the discharged fine dust flows into various components for generating a suction force, specially a fan motor, thereby damaging them.
Thus, to solve above problems, a separate filter should additionally be provided inside a body of the vacuum cleaner when the related art cyclone collector is applied to a vacuum cleaner.
Accordingly, the present invention is directed to a device for reducing pressure loss of a cyclone dust collector that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a device for reducing pressure loss of a cyclone dust collector, in which a turbulence flow generated when inlet air into a cyclone body is discharged out through an air outlet passage can be laminated.
Another object of the present invention is to provide a device for reducing pressure loss of a cyclone dust collector, in which fine dust as well as relatively weight dust is prevented from being contained in discharge air.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objects and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a device for reducing pressure loss of a cyclone dust collector includes: a cyclone body; an air inlet passage connected with the cyclone body, for sucking air and foreign materials; an air outlet passage for discharging the air sucked into the cyclone body; a foreign material outlet hole for discharging the foreign materials separated from the air in the cyclone body; and a laminar flow means provided on an axial line along the air outlet passage, wherein the air discharged through the air outlet passage loses its rotative force by the laminar flow means so that air flow in the air outlet passage and the air inlet passage is laminated.